Analysis on the development of core positioning parameters of GPS navigation message

This paper summarizes the development process of GPS spatial signal interface control file, and compares the message structure and broadcast mode of three existing navigation message types. The development characteristics and improvement effects of ephemeris parameters, clock error parameters and integrity parameters are analyzed in detail. The analysis results show that the new GPS navigation message provides high accuracy of broadcast ephemeris and clock error products by increasing the core positioning parameters and reducing the quantization unit. After adding two parameters, the average root mean square (RMS) value of the ephemeris fitting position error is reduced from 0.137 m to 0.025 m. In order to adapt to the high-precision ephemeris fitting model, the distance quantization unit is also reduced to millimetre. By reducing the quantization unit of satellite clock error parameters, the RMS predicted 1 h clock error is reduced from 0.097 m to 0.042 m.